What’s next in federal vehicle emissions standards?

While heavy duty commercial vehicles make up only 5 percent of the vehicles on today’s U.S. roads, they account for nearly 20 percent of greenhouse gas (GHG) emissions from all classes of on-highway vehicles, according to the U.S. Environmental Protection Agency (EPA). This is one of the reasons the U.S. government has looked to regulate the amount of GHG emissions and continues to pursue ever-stringent standards. 

A bit of history

All vehicle emissions standards, including on-highway heavy duty truck emissions, stem back to the U.S. EPA’s Clean Air Act. Originally passed in 1963, the Clean Air Act is an environmental federal law that regulates GHG emissions to control air pollution. This includes standalone polluters such as power plants as well as any vehicle on the road today, passenger car through heavy duty truck.

Throughout the 1970s and 1980s, the U.S. EPA created and maintained emissions standards and created certification requirements for vehicles and engines. A 1997 ruling which impacted model year 2004 and newer trucks, regulated the levels of emissions produced from the combustion of fuels, including nitrogen oxide (NOx), hydrocarbons, and particulate matter (PM) emitted from heavy duty vehicles. This aimed to reduce NOx emissions by 50 percent. From there, regulations became increasingly more stringent at an expedited pace.

Finalized in 2001, the 2007 Heavy Duty Engine and Vehicle Rule further regulated emissions for heavy duty on-highway trucks. The updated emissions standards included a significant reduction in PM and NOx emissions emitted from on-road heavy duty diesel vehicles. PM includes soot, unburned hydrocarbons, ash, or sulfate. The PM emission standard took full effect in 2007 – coinciding with regulations to the 2007 model year phase. The NOx standard was phased in for diesel engines between 2007 and 2010.

Heavy duty diesel engine emission control systems, more commonly known as aftertreatment systems, were introduced as a solution to aid in reducing both PM and NOx emissions, since the pre-2007 fuel system, air handling, and combustion technologies were unable to complete these tasks up to government standards.

Diesel engines with aftertreatment systems must use ultra-low sulfur diesel (ULSD) — which was another U.S. EPA standard designed to help reduce pollutants in conjunction with limiting emissions. If a higher concentration of sulfur is in the fuel, it could damage the aftertreatment system.

In 2009, the U.S. EPA made a separate ruling requiring all heavy duty engines include an on-board diagnostics (OBD) system to monitor the emission control system, with functionality to send alerts to the driver when faults are detected. This same ruling required manufacturers to provide service information to complete the necessary repair and maintenance on the OBD system and any emission-related engine components. 

Continued aim to reduce GHG emissions

About the time OBD systems were becoming a requirement, the U.S. EPA worked together with the National Highway Traffic Safety Administration (NHTSA) to create the Heavy Duty National Program – more commonly referred to as Phase 1. The program was finalized in 2011. Phase 1 was a joint effort through both federal organizations to continue efforts on a further reduction in heavy duty vehicle GHG emissions while also adding fuel efficiency improvement considerations.

Phase 1 includes separate standards for the entire vehicle and the engine separately, for truck model years 2014 through 2018. Manufacturers could meet standards by implementing new technologies and by receiving emissions credits.

Finalized in 2016, the Phase 2 GHG emissions standards and fuel efficiency standards are a continuation of the Phase 1 regulations designed to further improve emissions and fuel efficiency for heavy duty vehicles. Phase 2 will impact vehicle and engine performance standards for medium and heavy duty truck model years 2021 through 2027, with more stringent requirements of each phase beginning in 2021, then 2024, and again in 2027.

The Phase 2 standards also initially included box trailers from 2018 through 2027 model years, while custom and flatbed trailers were not part of the official rulings. Recent legal developments, however, have delayed any type of requirement in this segment of the heavy duty industry.

Once in full effect, vehicles sold under and meeting final Phase 2 standards are expected to lower CO2 emissions by about 1.1 billion metric tons, save $170 billion in fuel costs, and reduce oil consumption by up to 2 billion barrels over the lifetime of the vehicles, according to the U.S. EPA’s Phase 2 final ruling documentation. 

Latest developments and the Cleaner Trucks Initiative

In early 2020, the U.S. EPA announced the introduction of an advanced notice of proposed rulemaking, or ANPRM, for the Cleaner Trucks Initiative (CTI). An ANPRM is not a proposed rule; it is a draft provided to stakeholders – which can be fleets, end-users, industry organizations, environmental groups, and more – in order to gather input and make revisions.

While the title of the CTI ANPRM does not outright state the proposed rulemaking’s focus, the proposed rule targets lowering NOx emissions limits even more than the current federal requirements. It is important to note that this is a separate proposal from the federal Phase 1 or Phase 2 regulations already in place.

“The low-NOx rule is going to be a separate, distinct rulemaking ramping down NOx emissions for new engines. The last NOx rule for trucking was finalized in January 2001,” says American Trucking Associations’ Energy and Environmental Counsel Glen Kedzie, of the Phase 1 GHG emissions standards. The Phase 1 standards were first enforced on 2007 model year on-highway trucks.

While trucking is federally regulated, operations of that vehicle are also beholden to state regulations. Case in point, the state of California has more stringent vehicle design and operating regulations for heavy duty trucks compared to federal rules. California has one of the worst air quality measurements in the country, says Kedzie, and must focus on continually improving that air quality dictated by the Clean Air Act requirements. With this, the California Air Resource Board (CARB) and state lawmakers have taken additional steps to lower GHG emissions, particularly the focus on a further reduction in NOx.

“Given the significant ozone and PM air quality challenges in the state of California, CARB has taken a number of steps to establish standards beyond the current EPA requirements to further reduce NOx emissions from heavy duty vehicles and engines in their state,” notes the CTI ANPRM document. A voluntary state program created in 2013 was designed to allow manufacturers to certify engines emitting lower levels of NOx. There are three tiers of certification levels, with the highest being a 90 percent reduction in NOx emissions from the 2010 federal NOx emissions regulations. To date, natural gas and liquefied petroleum are the only two engine types that have been certified at this lowest NOx-emitting level.

While the U.S. EPA has followed suit with the latest CTI proposal, it is in the beginning stages of a regulation compared to the progress made so far by CARB. “You have California trying to finalize something in the next couple of months, and EPA is still trying to bounce concepts off the stakeholders,” Kedzie says.

The disparity currently is that CARB is looking to enact these lower NOx emission level requirements in the state of California for 2024. The earliest possible implementation at the federal level, according to the CTI proposal, would be 2027.

“There’s going to be a regulation going forward,” Kedzie says. “We can either let California drive the direction of it or we can work with those that we’re accustomed to working with [at the federal level] using our data, hoping that we’ll get a better shake at the end of the day. It makes more sense for us to have one national standard, implemented in a reasonable glidepath, using sound science [and] thoroughly tested technologies.”

Kedzie adds that considerations should be taken when establishing this next round of national emissions standards. It is imperative that new technology to reduce NOx does not negatively impact existing system designs that may cause “fuel economy hits” or in other ways increase other GHG emissions.

When it comes to this latest proposal, the CTI is also designed to ensure that manufacturers can focus on developing products, systems, and vehicles that will meet the needs of the latest Phase 2 GHG and fuel efficiency standards, as well as the NOx reduction technologies. 

How does this impact my fleet?

The GHG emission and fuel efficiency regulation enforcement starts with manufacturers and suppliers certifying their products meet the federal regulations. This is done through testing and validation during development and production.

While the industry must rely on the vehicle manufacturers and parts suppliers to ensure these regulations are met, it is imperative that fleets do their part as well. Drivers and fleets have a responsibility once that vehicle is in operation to ensure upkeep and compliance. Compliance, Safety, Accountability (CSA) roadside vehicle inspections provide some form of oversight. Additionally, fleets must consider the importance of managing any diagnostic trouble codes and subsequent repairs to ensure the most efficient vehicle operation.

This also means keeping assets maintained on regular interval schedules, and adhering to manufacturer service guidelines, say truck manufacturers.

“We recommend following OEM maintenance and preventive maintenance guidelines and reviewing spec sheets to understand [what] was originally spec’d,” says Kelly Gedert, director, product marketing, Freightliner and Detroit Components. “It is important to maintain similar components to not affect the compliance of a vehicle.”

“Vehicle and engine OEMs will add information into the operator’s manual about which parts and systems may be GHG emission-related and therefore need to be replaced with the same or better-performing parts. The vehicle must be maintained in the same configuration and in good working order as when the vehicle was built,” adds Carl Hergart, director of powertrain and advanced engineering at the Paccar Technical Center. The Paccar Technical Center provides testing and development for the company’s Kenworth, Peterbilt, and DAF truck lines. Hergart suggests using sound judgment when it comes to service or parts replacement, to validate the modifications would not indirectly or directly increase vehicle emissions. 

What’s next?

The original Phase 2 regulations, for the first time, included trailers as part of the emissions regulations. However, in October of 2017, the Truck Trailer Manufacturers Association (TTMA) petitioned to have trailers removed from the regulations. This request was granted and requires further review from the U.S. EPA. As it stands today, the trailer category is not being considered as part of the Phase 2 emissions standards. It is important to note, a similar emissions regulation in California dictated a similar provision for trailers. That provision has been stayed for two years.

In part due to federal regulations and due to improve total cost of ownership, designs for heavy duty on-highway trucks will continue to change. With that, updates to the design and function of these vehicles will also have a direct impact on vehicle service and maintenance methods.